1. Field of the Invention
The present invention relates to a locking slide bar or clasp of the type used to form a stiff spine for reports, sales or marketing presentations, and other stacks of paper assembled and bound together.
2. Description of the Prior Art
Plastic spines or slide bars for use in gripping the binding edges of stacks of papers together, such as reports, proposals, briefs, and other stacks of documents fastened together along a common edge have been manufactured for many years. Conventional report cover grips or slide bars of this type are manufactured as extruded plastic structures of uniform cross section throughout. Conventional slide grips are formed with a pair of jaws joined together at a common base and forming an open slot or gap therebetween. The jaws are longitudinally elongated so as to extend the entire length of the binding edge of the stack of papers. The gap between the jaws is narrow enough so that they must be forced apart slightly to accommodate the thickness of the stack of papers. The jaws can be deflected resiliently apart to increase the width of the gap therebetween so as to receive the binding edge of the stack of papers within the gap. When the jaws are released, a clamping force is exerted by the jaws against the stack of papers as the jaws attempt to move toward each other back toward their undeformed positions.
A major problem with conventional slide grips or slide bars of this type is that the gripping force is frequently inadequate to secure the grip on the binding edge of the stack of papers. Quite often, when a user opens the report, the stress of parting the papers as the pages are opened is transmitted to the slide grip as a force directed outwardly away from the longitudinally oriented binding edge of the report in a direction perpendicular thereto. As a consequence, the slide grip is pushed laterally away from the binding edge and pops off the binding of the report. This tendency is aggravated when the report has a clear, slick, glossy cover, such as a clear plastic polypropylene cover of the type frequently used as a report or presentation cover to protect the papers therewithin. The low coefficient of friction on the surface of such a plastic cover makes it extremely easy for a conventional spine-gripping bar to pop off of the binding edge of a stack of bound papers when the pages are opened.
Attempts have been made to correct this problem. For example, the otherwise conventional sliding bar report cover grip sold by the JM Company located in Hasbrouck Heights, N.J. has a report cover gripping bar provided with a pair of opposing longitudinal ribs directed toward each other near the bases of the jaws of the grip. The concept is that the additional contact with the cover provided by the ribs will enhance the gripping force provided by the slide bar on the cover. However, this system provides no positive interlocking connection between the slide bar and the report cover so that the report cover grip still slides free from the cover when the report is opened.
The Avery Dennison Company has used a gripping report cover slide bar on which the extremities of the jaws are provided with inwardly directed hooks or tangs. This system is described in U.S. Pat. No. 5,865,469. A polyethylene plastic report cover is folded in half and die cut near its longitudinal center fold with a plurality of arcuate, semicircular die cuts spaced periodically along its length to create a number of tabs. The curved surfaces of the semicircular tabs are directed away from the binding center fold and toward the opposite edges of the cover and of the stack of papers encompassed therewithin. However, this system still has several problems. Because the semicircular tabs lie in the same plane as the cover sheet material from which they are cut, the hooked edges of the gripping bar will sometimes fail to engage the semicircular tabs. Also, the die cuts are through both the front and back cover of the folded polyethylene cover sheet and must be spaced quite closely to the center fold line in order to be engaged by the hooks or tangs at the extremities of the jaws of the gripping bar. There is very little structure left between the front and back die cuts adjacent the fold line. As a consequence, the material can fail at the fold line and the tabs will separate from the remaining structure of the cover as generally circular die cut punch outs.
To solve these and other problems I previously devised a different system for creating a spine for a report or other stack of papers. This system is described in my prior U.S. Pat. No. 6,270,120, which is hereby incorporated by reference in its entirety. Specifically, in that system I utilize a slide bar that has a pair of jaws that terminate in hooked lips that face each other across a gap defined between the jaws. The narrow margin panel atop the binding edge of the report is captured by the hooked lip of one of the jaws throughout its length. The positive locking interengagement of the narrow binding margin panel in the hooked lip prevents the slide bar from being pulled laterally off of the binding edge of the stack. While this system works quite successfully, it""s still involves the necessary step of securing the binder to the stack of papers by means of fasteners, such as staples. This involves an extra step in the preparation of reports and other documents. Where many copies of such documents are required, this extra step adds considerably to the time and expense involved in preparing bound reports and other documents for distribution.
The present invention is an improved type of document binding cover grip bar system that overcomes the deficiencies of the prior art. Specifically, I have discovered that by configuring the jaws of the slide bar so as to more directly oppose each other to form a clamp, the clasp created exerts such a firm grip on the binding and stack of papers enclosed therewithin that it is no longer necessary for the cover to be fastened to the stack of papers encompassed therebetween by any other fasteners. Moreover, with the proper orientation of the jaws, it is unnecessary to provide the distal tips of the jaws with hooked lips in order to capture both the cover and the stack of papers encompassed therebetween even without the use of other fasteners, such as staples.
By orientating the distal tips of the clamping jaws of the slide bar in direct opposition to each other at an angle of no less than about forty-five degrees, a slide bar constructed according to the present invention firmly grips a narrow margin binding panel or strip of a cover, as well as a stack of papers located within the cover, without the use of any other type of fastening system. The clamping slide bar of the present invention prevents the papers within a stack of papers folded within a document cover from pulling free from the cover and does not require a separate die cutting operation to create tabs from the cover for the clamping jaws to grip. Furthermore, the system of the present invention is not susceptible to structural failure within a plastic cover, since there are no tabs cut into the structure of the cover.
In one broad aspect the present invention may be considered to be a combination of a plurality of sheets of paper, a document cover, and a stiff, resilient, elongated channel-shaped clasp which engages the document cover. The sheets of paper are disposed one atop another to form a stack having top and bottom sheets and defining a binding edge of the stack. An opposite edge of the stack is parallel to the binding edge while a narrow binding margin on the stack lies adjacent to the binding edge. The document cover is formed of a plurality of panels, including a front cover panel located atop the stack and above the top sheet and a back cover panel located beneath the stack and residing below the bottom sheet of the stack and having a margin portion located beneath the binding margin. Another of the document cover panels is a narrow margin binding panel having a width no greater than the width of the binding margin of the stack. The front cover panel is formed of a separate sheet of material from the back cover panel and the narrow margin binding panel and overlaps and is permanently secured to the narrow margin binding panel.
The channel-shaped clasp is of uniform cross section throughout and is formed with a pair of jaws joined together and projecting outwardly from their junction to form distal tips that define a gap therebetween. The jaws are oriented in opposition relative to each other. The distal tips are directed toward each other to form an angle therebetween of at least about forty-five degrees. The binding edge of the stack, the narrow margin binding panel, and the margin portion of the back cover panel are inserted in between the jaws with the remainder of the stack and document cover projecting through the gap so that the distal tip of one of the jaws is engaged with the narrow margin binding panel to restrict relative movement between the clasp and the stack in a direction perpendicular to the binding edge.
Preferably, the jaws of the clamp are oriented relative to each other at an angle of about ninety degrees, and the gap between the distal tips of the jaws has a width of no greater than about fifty mils when the clasp is in an undeformed condition. The front cover panel is formed of a separate, first sheet of material while the other binding panels are formed of a second, separate sheet of material. The back cover panel is a broad back cover that extends from the binding edge of the stack all the way across to the opposite edge of the stack beneath the bottom sheet thereof and is separated from the narrow margin binding panel by at least one fold at the spine of the binder. With a construction such is this, the back cover panel and the narrow margin binding panel of the document binder may be formed of paper, card stock, or plastic, such as polyethylene or polypropylene. A separate, clear, transparent polyethylene sheet may serve as a front cover panel for the cover and may be attached to the underside of the narrow margin binding panel by adhesive or sonic welding above the binding margin of the stack of papers. Alternatively, the front cover may be constructed of some other plastic, such as polypropylene or Mylar, or it may be constructed of paper or card stock as well.
The invention may be defined in another way as a combination of a plurality of pages, a cover, and a stiff, resilient, elongated clasp of uniform cross section throughout. The pages are disposed one atop another to form a stack having top and bottom sheets and defining a binding edge of the stack. An opposite edge of the stack is parallel to the binding edge. The stack has a narrow binding margin adjacent to the binding edge. The cover for the stack includes a first sheet of material forming a margin panel and a back cover panel respectively residing in contact with the top and bottom sheets of the stack. The cover panels of the first sheet of binding material are joined together by at least one spine fold located at and parallel to the binding edge of the stack. The narrow margin panel has an exposed side and an underside that extends the length of the binding margin and is limited in width so that it extends no further toward the opposite edge of the stack than the binding margin. The narrow margin panel thereby defines an inboard boundary proximate the binding margin. The second sheet of cover material forms a front cover panel that is permanently secured to the underside of the narrow margin panel.
The clasp is formed as a channel-shaped structure having a pair of opposing jaws that have mutually facing distal tips oriented in opposition relative to each other and which form an angle therebetween of at least about forty-five degrees. The distal tips of the jaws also define a slot opening therebetween. The distal tip of one of the jaws is disposed to capture the cover therewithin, whereby the distal tip of one of the jaws engages the inboard boundary of the margin panel. The clasp is thereby held on the binding edge of the stack.